The invention relates to a method and apparatus for forming a flat panel display by combining a plurality of individual display devices.
The size of an individual display device such as a liquid crystal display (LCD) element typically is limited by acceptable manufacturing yields using currently known techniques and tools. It is therefore advantageous to be able to combine several display devices together to produce either a larger display or to mount individual display devices in various positions on a larger display panel. For example, in the computer, television, and entertainment industries, large area displays of a size much larger than single display device sizes are desired for viewing by groups of people or single individuals. In such applications, close placement-and alignment of display devices to each other are critical parameters in order to make the edges of the display devices inconspicuous, that is, to ensure no breaks are visible as information is viewed across the boundaries from display device to display device. Automotive and aircraft dashboard panels may require information such as speed, temperature, and fuel level to be displayed in various positions, sometimes with large gaps between these positions, on a large overall display panel.
One method of forming a display panel is to clamp individual display elements between two glass plates using screws or other tighteners and brackets of various design about the edges of the glass plates. Individual display elements may then be viewed through one of the glass plates. The display can be illuminated, if necessary, by placing a light source behind the second glass plate. Such a method is set forth, for example, in U.S. Pat. No. 4,156,833, the entire disclosure of which is hereby incorporated by reference.
Both the illuminating radiation (hereinafter referred to as xe2x80x9clightxe2x80x9d) as well as the display device image must, of necessity, pass through one or more of the glass plates. Optical properties of the glass plates (such as the transmission/absorption spectrum, and reflectance properties both surfaces) are important design parameters that can affect display panel performance. These parameters can possibly cause reductions in brightness, contrast, and resolution. Consequently, it is important to select a glass material and surface treatment with care and to minimize the number of layers and interference surfaces through which the images and illuminating light must pass. Obvious variations of this overall structure are possible using optically transparent materials other than glass, such as various plastics, or even opaque materials, for the backplate in applications where reverse illumination is not needed.
Placing and holding individual display devices in accurate alignment prior to clamping the glass plates together has been difficult to achieve due to extremely precise requirements on alignment accuracy and the possibility of shifting one or more devices previously aligned as others are added prior to clamping all of these in place.
It is also beneficial to provide a seal to prevent dust, moisture, and/or other contaminants, from entering the display panel after assembly. Including a seal during clamping can add complexity and difficulty to the clamping process. methods which are the subject of other patents have been developed for making electrical connection to each of the display elements, or for providing electrical interconnection between these. Connections can be made by overlapping edges of display elements as shown in U.S. Pat. Nos. 5,164,853 and 4,408,836 and Japanese patent JA 0302222, or by abutting corresponding conductive pads on edge surfaces of adjacent display elements as shown in U.S. Pat. No. 5,067,021. The entire contents of the four patents immediately above are hereby incorporated herein by reference. Any of the above or other connection schemes can be employed in the present invention.
It is an object of the present invention to provide a device for aligning and attaching a plurality of display devices to provide a larger display.
Another object of the present invention is to provide a method for aligning and attaching a plurality of display devices utilizing the apparatus.
In accordance with these and other objects and advantages, the present invention provides a method for aligning a plurality of thin film transistor display devices or tiles for constructing a flat panel display. A coverplate is arranged on a coverplate support. A first layer of a bonding material is applied to at least one of a first side of each of the tiles and a surface of the coverplate on which the tiles are to be secured. The tiles are arranged on the coverplate such that the first layer of bonding material is arranged between the tiles and the coverplate. The tiles are connected to an alignment apparatus. The tiles are aligned relative to each other and/or relative to the coverplate. The tiles are then at least partially secured to the coverplate. A second layer of a bonding material is applied to at least one of a second side of each of the tiles and a surface of a backplate to be secured to the tiles. The backplate is arranged on the tiles, such that the second layer of bonding material is arranged between the backplate and the tiles. The backplate is aligned relative to the tiles. The backplate is at least partially secured to the tiles. Then, the first layer of bonding material and the second layer of bonding material are fully cured, thereby attaching the tiles to the coverplate, the backplate to the tiles, and the tiles to each other.
Additional aspects of the present invention provide an apparatus for aligning and attaching together a plurality of thin film transistor tiles for constructing a flat panel display. The apparatus includes a coverplate support for supporting a coverplate that the tiles are to be attached to. The apparatus also includes a tile engager, a tile position alterer and a detector for detecting the position of the tiles relative to each other and relative to the coverplate. The apparatus further includes apparatus for at least partially securing the tiles to the coverplate. The apparatus further includes apparatus for at least partially securing the tiles to the coverplate. The apparatus further includes a backplate engager for engaging a backplate arranged on the tiles, a backplate position alterer for altering a position of the backplate, and apparatus for at least partially securing the backplate to the tiles.
Still other objects and advantages of the present invention will become readily apparent by those skilled in the art from the following detailed description, wherein it is shown and described only the preferred embodiments of the invention, simply by way of illustration of the best mode. contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.